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A review on the application of thermogravimetry (TG) in the field of fiber-forming organic high polymers is given by examples from the literature and from the work of the author. The investigation of the relative thermostability, their changes by modification of the polymers or by addition of stabilizers and the calculation of kinetic values are particularly stressed. The advantage of derivative thermogravimetry and the necessity for isothermal thermogravimetric investigation to characterize the longtime behaviour of polymers are explained. Finally, general limitations of, and recommendations for, the application of TG, e.g. the combination with other methods of investigation, are mentioned.

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The possibility of describing the kinetics of thermal degradation of PVC samples under both isothermal and nonisothermal conditions with a unique model and using the same set of parameters was investigated. Analysis of the experimental data revealed good agreement at higher temperatures (above 175 °C) when the catalytic action of generated HCl and its distribution in the sample were considered. At lower reaction temperatures, further experimental conditions and/or sample characteristics must be considered, and a modification of the model is necessary.

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Formalkinetische Behandlung des Masseverlustes bei thermischen Abbauprozessen von Polymeren unter nichtisothermen Bedingungen

III. Auswertung experimenteller TG-Kurven am Beispiel des Abbaus von Polyphenylen

Journal of Thermal Analysis and Calorimetry
Authors:
J. Behnisch
,
E. Schaaf
, and
H. Zimmermann

Kinetic values from non-isothermal thermogravimetric curves of polyphenylene have been calculated using the method of Flynn and Wall and that of Zsakó. These methods at first give unreal kinetic parameters, for it has been established that the degradation of polyphenylene is a system of two mutually independent reactions occurring simultaneously. With the use of a special relation between the degree of conversion of the unit reaction and that of the components, the kinetic parameters of the two reactions could be investigated by the method of Zsakó.

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On the basis of the formal basic relation
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\frac{{d\alpha }}{{dt}} = A \cdot e^ - \frac{E}{{RT}}(1 - \alpha )^n$$ \end{document}
methods of calculating kinetic values from non-isothermal thermogravimetric curves have been critically evaluated. It has been established that in general integral methods are preferable to differential methods. Methods basing on a series expansion of the exponential integral
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$\int\limits_0^T {e^ - \frac{{ET}}{{RT}}} dT$$ \end{document}
are applicable without limitations to any cases. It has been concluded that the integral method suggested by Zsakó is the most reliable.
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Methods of calculating kinetic values from non-isothermal thermogravimetric curves obtained at different heating rates have been critically evaluated. It has been established that these methods give unreal kinetic parameters, when applied to a system of two mutually independent reactions occurring simultaneously. Cases in which components of the unit reaction could be investigated by the method of Zsakó are discussed.

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Journal of Radioanalytical and Nuclear Chemistry
Authors:
A. Türler
,
H. Gäggeler
,
K. Gregorich
,
H. Barth
,
W. Brüchle
,
K. Czerwinski
,
M. Gober
,
N. Hannink
,
R. Henderson
,
D. Hoffman
,
D. Jost
,
C. Kacher
,
B. Kadkhodayan
,
J. Kovacs
,
J. Kratz
,
S. Kreek
,
D. Lee
,
J. Leyba
,
M. Nurmia
,
M. Schädel
,
U. Scherer
,
Schimpf
,
D. Vermeulen
,
A. Weber
,
H. Zimmermann
, and
I. Zvara

Abstract  

On-line isothermal gas phase chromatography was used to study halides of261104 (T1/2=65 s) and262,263105 (T1/2=34 s and 27 s) produced an atom-at-a time via the reactions248Cm(18O, 5n) and249Bk(18O, 5n, 4n), respectively. Using HBr and HCl gas as halogenating agents, we were able to produce volatile bromides and chlorides of the above mentioned elements and study their behavior compared to their lighter homologs in Groups 4 or 5 of the periodic table. Element 104 formed more volatile bromide than its homolog Hf. In contrast, element 105 bromides were found to be less volatile than the bromides of the group 5 elements Nb and Ta. Both 104 and Hf chlorides were observed to be more volatile than their respective bromides.

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